1. Field of the Invention
This invention relates to a personal computer and more particularly to a heat exchange device and system coupled to a computer keyboard for dissipating thermal energy within the personal computer.
2. Background of the Relevant Art
A computer system is one which, at a minimum, includes an input/output (I/O) port, a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), an address bus, a control bus, and a data bus. Depending upon its complexity, a computer system can be classified as a mainframe, a minicomputer or a microcomputer. Mainframe computers, often termed supercomputers, have in many instances today been replaced by smaller, less costly minicomputers. The term minicomputer is therefore used to denote a general purpose personal computer used for computation, process control, word processing, etc. Many workstation minicomputers use graphic-intensive programs and are therefore used for more specialized functions such as computer-aided design (CAD) and computer-aided engineering (CAE). A minicomputer typically employs a motherboard having separate I/O control, CPU, ROM and RAM2 integrated circuits arranged upon the motherboard. A microcomputer, on the other hand, generally incorporates I/O control, CPU, ROM and RAM functions on a single monolithic silicon substrate. Depending upon its application, a single chip microcomputer is often denoted as a microcontroller (MCU).
Regardless of the type of computer system used, the CPU often generates large amounts of thermal energy (or heat) during its operation. Advances in CPU speed and bus throughput have further compounded this problem. Large mainframe computers are usually cooled by forcing cool air or liquid coolant over the CPU heat source. A microcomputer, on the other hand, is generally designed to operate at lower voltages and/or speed, thereby avoiding higher temperature operation. Constrained to application performance demands, a minicomputer, however, must operate at a higher speeds and voltages than a microcomputer. Yet, a minicomputer is not afforded the high costs necessary to cool supercomputing mainframes.
Most minicomputers of the desktop variety are thermally managed by forcing air across the motherboard and particularly across the CPU. Forcing air in such a manner requires a fan placed upon the minicomputer chassis and, in some instances, an additional fan placed directly above the CPU. In lieu of or in addition to a fan, many minicomputer manufacturers often employ a heatsink. A heatsink is generally made of metal having opposed surfaces, wherein one surface is mostly flat while the other surface includes a plurality of outward-extending fins. The flat surface is thermally bonded to the encapsulated CPU, allowing the fins to project into the airplow stream carried through the minicomputer chassis. A silicon compound is normally used as the thermal bonding agent. The metal fins function similar to a metal radiator in that they remove heat from the thermally bonded, underlying CPU by means of conduction, convection and radiation.
Fans and heatsinks provide a cost effective mechanism for thermally managing many types of minicomputer systems. Fans, however, require power and heatsinks require space. While power and space are generally in abundant supply in desktop-type minicomputers, portable minicomputers (often termed "laptop computers") have only a limited supply of both power and space. A commercial advantage is achieved by manufacturing portable computer that are both small and lightweight. Further, portable computers must operate with power conservation in mind. An operable fan would unduly draw upon the batteries of a laptop making it unattractive for long periods of battery-operated use.
A need therefore exists for a thermal management system within a portable computer which is both cost effective and operably superior to conventional fans and finned heatsinks. Thermal management of portable computers has become an even more important consideration with the advent of higher speed CPUs, or CPUs having advanced 32-bit and 64-bit bus structures. As an example, Pentium.RTM.-based CPUs generate considerably more thermal energy than predecessor x386 and x486 CPUs. In order to effectively use a Pentium.RTM.-based CPU within a portable computer, it becomes necessary that heat be efficiently drawn away from the CPU absent the use of bulky finned heatsinks and power consumptive fans.